Thermal ionization and thermally activated crossover quenching processes for5d−4fluminescence inY3Al

Abstract

We investigated thermally activated ionization and thermally activated crossover as the two possibilities of quenching of 5d luminescence in Pr 3+ -doped Y 3 Al 5−x Ga x O 12 . Varying the Ga content x gives the control over the relative energy level location of the 5d and 4f 2 :3 PJ states of Pr 3+ and the host conduction band (CB). Temperature-dependent luminescence lifetime measurements show that the 5d luminescence quenching temperature T 50% increases up to x = 2 and decreases with further increasing Ga content. This peculiar behavior is explained by a unique transition between the two quenching mechanisms which have an opposite dependence of thermal quenching on Ga content. For low Ga content, thermally activated crossover from the 4f 5d state to the 4f 2 ( 3 PJ ) states is the operative quenching mechanism. With increasing Ga content, the activation energy for thermally activated crossover becomes larger, as derived from the configuration coordinate diagram, while from the vacuum referred binding energy diagram the activation energy of thermal ionization becomes smaller. Based on these results, we demonstrated that the thermal quenching of Pr 3+ : 5d 1 -4f luminescence in Y 3 Al 5−x Ga x O 12 with x = 0, 1, 2 is a thermally activated crossover while for x = 3, 4, 5 it results from the thermal ionization.

Local coordination, electronic structure, and thermal quenching of Ce3+ in isostructural Sr2GdAlO5 and Sr3AlO4F phosphors

“…The thermal ionization induced thermal quenching probability can be vividly understood in an VRBE diagram . A U (6,A) (the inter 4 f ‐electron Coulomb repulsive force of Eu 2+/3+ in site A) value is crucial for the VRBE construction; but since we are unable to observe/identify all 4 f ‐5 d 1‐5 transitions of Ce 3+ in both hosts, the empirical way using Equation to estimate U (6,A) from Ce 3+ ε c does not work.…”

Single crystal growth, optical absorption and luminescence properties under VUV-UV synchrotron excitation of type III Ce3+:KGd(PO3)4, a promising scintillator material

“…This same procedure was used in the work done by Ueda et al . 41 . Then, the estimated value of E ex has been obtained by adding 0.35 eV to E fa since these measurements have been performed at room temperature 42 .…”

Charge Carrier Trapping Processes in RE2O2S (RE = La, Gd, Y, and Lu)

“…Figure S2 shows that at 10 K Ti 4+ CT excitation band locates at ∼327 nm (3.79 eV). Figure S3 shows that the temperature T 0.5 where Ti 4+ emission intensity is quenched by 50% is at ∼165 K. The activation energy for thermal quenching can be derived from 29 where I ( T ) and I (0) is the luminescence intensity at temperature T and 0 and E indicates the activation energy. A fit through the data in Figure S3 , as indicated by the solid curve provides the activation energy E = 0.05 eV.…”